The adequacy of outpatient medical services for intravenous drug users (IVDU), women and children with AIDS is largely dependent on the quality and accessibility of providers enrolled in publicly funded health care programs. This project will investigate patterns of provider care for more than 20,006 Medicaid AIDS patients in New York (NY) and California (CA) using longitudinal files of Medicaid claims from 1982-90 that are specifically constructed for research purposes. An established research team will conduct the project drawing upon their expertise in disease staging, small area variation techniques, and analyses of resource use and clinical outcomes of Medicaid AIDS patients. Our goals are to: 1) Identify outpatient provider patterns that result in high inpatient or emergency room use, or greater severity of illness than expected, and compare patterns of care by risk group. 2) Determine the impact of provider patterns and types of informal caregivers on the clinical course and medical resource use of children with AIDS. 3) Examine access to care by determining geographic overlap between the incidence of AIDS patients with supply of AIDS providers over time. 4) Analyze small area variations between communities in NY and CA in outpatient care patterns, hospitalization rates, lengths of stay, and mortality during or just after hospitalization. 5) Study the types of conditions and associated morbidity experienced by HIV-infected individuals prior to the diagnosis of AIDS, and trace changes in providers as the disease becomes increasingly complex to manage. These analyses will inform policymakers as they decide on the types of outpatient care settings to promote for AIDS, guide the selection of sites or population groups having the greatest need for educational interventions, and produce a better understanding of patterns and outcomes of care for the disadvantaged, including minorities and children with HIV infection.